NEW DETAILS: Kiefer Sutherland's "Head-Butting" Under Investigation

A late night "head-butting" incident involving actor Kiefer Sutherland at a club in New York is "under investigation", a NYPD source tells RadarOnline.com.

Published reports today say Kiefer -- the star of FOX's hit drama 24 -- was apparently intoxicated when he got into an altercation with fashion designer Jack McCollough late Monday night at the SoHo nightspot SubMercer.

Witnesses say Kiefer was having a 2 a.m. conversation with actress Brooke Shields when McCollough bumped into the actress. The celebs were partying following attendance earlier in the evening at the Costume Institute’s gala at the Metropolitan Museum of Art.

McCollough was quoted as saying Kiefer “was drunk and obnoxious” and “pulled this stupid wrestling move like a teenager,” slamming him in the face.  MCCollough denied some reports that he suffered a broken nose but confirmed he received a small cut on his nose.

The NYPD could charge Kiefer with a misdemeanor and cops from the 1st Precinct in Manhattan are reportedly seeking him for his side of the story.

The NYPD source told RadarOnline.com: “What we have right now is a complaint by one of the people involved, which we are checking out. The District Attorney’s Office is aware of the investigation.”

In a strange twist, Shields rep said there was no exchange between the actress and McCollough, and the cause of Sutherland's outburst was unknown. Police were slated to interview the actress Wednesday about what happened, according to the Web site.

Shields may speak to police today.

New York social blog Guest of a Guest reported that other stars, including Mary-Kate Olsen and Kirsten Dunst, witnessed the incident.

Sutherland, 42, is currently on probation in Los Angeles in connection with a drunken driving conviction. (Photo: Splash News)